Field of the Invention
The present invention relates to a diagnostic method, an ID module, and a process control system. More specifically, the present invention relates to a method of diagnosing the type of field device in a process control system that controls a plurality of non-intelligent field devices, an ID module which is connected to the field device, and a process control system.
Priority is claimed on Japanese Patent Application No. 2015-160165, filed on Aug. 14, 2015, the content of which is incorporated herein by reference.
Description of Related Art
All patents, patent applications, patent publications, scientific articles, and the like, which will hereinafter be cited or identified in the present application, will hereby be incorporated by reference in their entirety in order to describe more fully the state of the art to which the present invention pertains.
Hitherto, in plants, factories and the like, process control systems that control various state quantities (such as, for example, pressure, temperature, flow rate) in industrial processes have been constructed, and a high level of automatic operation has been realized. The process control systems are provided with field devices (measuring instruments or operating instruments) called a plurality of field devices. Each of the field devices is connected to a controller through an I/O port (I/O circuit or input and output circuit), and the controller controls the operating instrument (for example, actuator) in accordance with measurement results of the measuring instrument (for example, sensor). Thereby, various state quantities are controlled.
There are various kinds (signal types) of field devices which are used in the process control systems in accordance with an object to be measured and an object to be operated, and there are also various types of signals which are input and output. For example, there are a type for inputting and outputting an analog signal of “4 to 20 mA”, a type for inputting and outputting a digital signal of “24 V”, a type for inputting and outputting a contact signal, a type for outputting a thermocouple signal, and the like. Therefore, in the process control systems of the related art, an I/O circuit (input and output circuit) corresponding to the field device is provided for each field device.
The number of field devices provided in the process control system increases or decreases in accordance with the scale of a plant or the like. The number of field devices may exceed ten thousand in a large-scale plant or the like, and it takes too much time and labor for wiring the field devices in the entire process control system. Therefore, a reduction in the time and labor of wiring leads to a large reduction in costs in the entire process control system.
The following Specification of U.S. Pat. No. 8,392,626 discloses a circuit (hereinafter, referred to as a universal circuit) capable of connecting field devices that input and output the analog signal or field devices that input and output the digital signal which account for a large majority of field devices. Specifically, the universal circuit disclosed in the Specification of U.S. Pat. No. 8,392,626 is a circuit capable of inputting (A/I) the analog input signal, outputting (A/O) the analog output signal, inputting (D/I) the digital input signal, or outputting (D/O) the digital output signal. An I/O module (input and output module) including a plurality of universal circuits has a plurality of channels. Since a field device can be connected to each of the channels of the I/O module, one I/O module can connect to multiple types of field devices.
Initially, wiring (marshaling) between the field device and each channel of the I/O module is performed. After the wiring is completed, an I/O mode (any of the input (A/I) of the analog input signal, the output (A/O) of the analog output signal, the input (D/I) of the digital input signal, or the output (D/O) of the digital output signal) of each channel of the I/O module is configured in accordance with the type of field device. Thereby, wiring (marshaling) between a terminal block to which the field device is wired and connected and the I/O module is not required, and thus the efficiency of field work such as wiring work is achieved. In addition, as compared with the providing of an I/O circuit corresponding to the type of field device for each channel, a reduction in costs can be expected by connecting multiple types of field devices to a plurality of channels of one I/O module.
The following Japanese Unexamined Patent Application, First Publication No. 2015-87975 discloses an I/O module capable of connecting more types of field devices than ever before. Specifically, the I/O module disclosed in Japanese Unexamined Patent Application, First Publication No. 2015-87975 includes a base plate having a plurality of connection terminals to which a plurality of field devices are electrically connected, a plurality of universal circuits which are provided in the base plate so as to correspond to the plurality of connection terminals, and an option module which is detachably provided in the base plate. Since any one connection terminal of the plurality of connection terminals provided in the base plate and a universal circuit corresponding to this connection terminal are connected to each other by the option module mounted on the base plate, and a field device connected to the connection terminal and the universal circuit are electrically connected to each other by a first circuit provided in the mounted option module, it is possible to connect more types of field devices than ever before.
A plurality of field devices are centrally managed in an upper layer device (device management terminal) through a network. The device management terminal manages the type of each field device and the arrangement location (wiring) thereof, and monitors whether abnormality is present or not. For this reason, the device management terminal is required to ascertain which field device is connected to each I/O port. Consequently, the device management terminal has a database that stores information about the type of field device which is connected to each I/O port. In a plant, the arrangement of field devices is often changed, and the database included in the device management terminal is required to be updated whenever the location (wiring) at which the field devices are arranged is changed.
In recent years, an intelligent field device having a function of allowing the field device itself to transmit information pertaining to itself through a network has been widely used. The information which is transmitted by this field device is matched with information of the I/O module, and thus it is possible to obtain information pertaining to wiring. In a case where the location (wiring) at which the intelligent field devices are arranged is changed, the intelligent field device itself transmits information pertaining to its own type or the arrangement location (wiring) thereof through a network, and thus the device management terminal can update a database by receiving the information. Thus, in a case where the intelligent field device is connected, it is possible to improve the efficiency of connection work and confirmation work to and for the I/O port.
However, the proportion of the intelligent field device to a total of field devices is approximately 50% as of 2015, and a non-intelligent field device has been widely used as of now. The non-intelligent field device refers to a field device which has no communication function and only deals with a signal pertaining to control. The non-intelligent field device does not transmit information pertaining to its own type or the arrangement location (wiring) thereof. For this reason, in a case where the non-intelligent field device is connected, which type of non-intelligent field device is connected to each I/O port is not able to be electrically confirmed on the I/O port side, and thus the confirmation has no choice but to be based on the visual confirmation of a worker in the field.
Depending on the scale of a plant, approximately 5,000 to 10,000 field devices are installed in the plant. In a case where the location (wiring) at which the non-intelligent field devices are arranged is changed, a worker needs to update a database included in the device management terminal, and thus the efficiency of work pertaining to wiring drops.